Standard Alarm Monitoring

 POTS (Plain Old Telephone Service)

Standard Alarm Monitoring

This type of alarm system monitoring has been the standard for years. It has always been very reliable but has always been vulnerable. It literally takes only minutes for a burglar to find the phone line coming into your home and cut the line. Once the line has been cut the alarm system “wants” to notify the central station but has no ability to transmit the signal.

While it provides limited features, low bandwidth and no mobile capabilities, POTS reliability is an often cited benchmark in marketing and systems-engineering comparisons, called the “five nines” reliability standard. It is equivalent to having a dial-tone available for all but about five minutes each year. Originally known as the Post Office Telephone Service/System (POTS) in many countries, the term was dropped as telephone services were removed from the control of national post offices. POTS is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world.

POTS has been available almost since the introduction of the public telephone system in the late 19th century, in a form mostly unchanged to the normal user despite the introduction of touch-tone dialing, electronic telephone exchanges and fiber-optic communication public switched telephone network (PSTN). Due to the wide availability of POTS, new forms of communications devices such as modems and facsimile machines are designed to use POTS to transmit digital information. In the United States, the pair of wires from the central switch office to a subscriber’s home is called a subscriber loop. The subscriber loop typically carries a “load” of about 300 ohms, and does not pose a threat of electrocution to human beings (although shorting the loop can be felt as an unpleasant sensation). It is typically powered by -48Vdirect current (DC) and backed up by a large bank of batteries (connected in series) in the central office, resulting in continuation of service during most commercial power outages.

The communications circuits of the PSTN continue to be modernized by advances in digital communications; however, other than improving sound quality, these changes have been mainly transparent to the POTS customer. In most cases, the function of the POTS local loop presented to the customer for connection to telephone equipment is practically unchanged and remains compatible with old pulse dialing telephones, even ones dating back to the early 20th century.

This type of communication for your alarm system is quickly becoming outdated and replaced with GSM monitoring. GSM monitoring is more reliable and offers features that could never be a reality with a standard phone line.


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